has failed and the engine is out of service. Therefore,
fuel systems. Identify procedures for repairing,
the types of maintenance consist of preventive
removing, and replacing diesel engine fuel sys-
maintenance (scheduled) and corrective maintenance
tem components.
(unscheduled).
Many of the diesel engines in support equipment
Preventive maintenance is performed periodically
are required to operate for long periods of time under
on the engine (and on the equipment on which it is
heavy loads. These engines are designed for this type of
used) in accordance with the MRCs. Corrective
use and can withstand it, provided they receive proper
maintenance is performed when a malfunction occurs
service and maintenance. Most of the servicing and
between periods of preventive maintenance.
maintenance requirements are simple, but nonetheless
important. Servicing the diesel engine includes the
Because a diesel engine depends on the heat of
compression for ignition and proper combustion, it is
some arrangements, hydraulic fluids and other
necessary for efficient operation that the engine run in
consumable materials. Maintenance is required to keep
the heat range specified by the manufacturer. If an
the diesel engine in an optimum operating condition.
engine is running too hot or too cold, check the cooling
system; this includes the water pump and fan belt. It
The similarity of the diesel and the gasoline engine
may be necessary to remove and test the thermostats.
is often pointed out, but in many ways they are
Pressure cooling systems are provided on most modern
dissimilar. This should be kept in mind during service
equipment. This enables an engine to operate at a
and maintenance of the engine. If there is any doubt as
higher temperature without boiling the coolant. The
to what you should do, consult the manufacturer's
pressure-relief valve in the system (usually in the
manual or other authorized publications.
radiator cap) should be checked periodically. If the
GENERAL SERVICING AND MAINTENANCE
pressure becomes too great, there is danger of blowing
a radiator hose or rupturing a tube in the radiator core.
Diesel engine servicing is normally done on a
If all diesel engines had nearly identical fuel
preoperational or periodic inspection and is performed
systems (like gasoline engines) trouble diagnosis and
in accordance with the MRCs (maintenance
maintenance procedures could follow a general pattern
requirements cards). These cards usually contain only
much like the one that is used for gasoline engines. But,
minimum requirements; therefore, it is the re-
with the exception of similar fuel tanks, filters, and a
sponsibility of the work center supervisor to review the
basic piping system, diesel engine fuel systems differ
cards and add additional requirements that are of
considerably. Consequently, each engine manufacturer
importance to the particular equipment in his operating
recommends different specific maintenance pro-
environment.
cedures. Those described herein for the more popular
The materials or products for servicing the diesel
diesels are by no means all you will need to know.
engine should be properly stored and kept free of
However, the tune-up and maintenance procedures
described are representative of jobs you will do. For all
rendered completely useless, or it may cause more
jobs you do not thoroughly understand, refer to the
damage than if the equipment was not serviced at all.
manufacturer's maintenance manual for the fuel system
concerned.
In servicing the diesel engine, you should use only
those materials or products recommended by the
DIRT IN THE FUEL SYSTEM
manufacturer or those that have been authorized as a
substitute by higher authority. Again, the maintenance
Many diesel engine operating troubles result
instructions for servicing, quantities, levels, etc., should
directly or indirectly from dirt in the fuel system. That
be followed.
is why proper fuel storage and handling are so
No matter how well the diesel engine is serviced
important. One of the most important aspects of diesel
and cared for, maintenance is still required to keep the
fuel is cleanliness. The fuel should not contain more
engine in optimum operating condition. The
than a trace of foreign substance; otherwise, fuel pump
maintenance performed on the engine falls into two
and injector troubles will occur. Diesel fuel, because it
broad categories: (1) actions taken to reduce or
is more viscous than gasoline, will hold dirt in
eliminate failure and prolong the useful life of the
suspension for longer periods. Therefore, you should
engine, and (2) actions taken when a part or component
take every precaution to keep the fuel clean.
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